/*
 *  gendisk handling
 */

#include <linux/module.h>
#include <linux/fs.h>
#include <linux/genhd.h>
#include <linux/kernel.h>
#include <linux/blkdev.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/seq_file.h>
#include <linux/slab.h>
#include <linux/kmod.h>
#include <linux/kobj_map.h>
#include <linux/buffer_head.h>
#include <linux/mutex.h>

struct subsystem block_subsys;
static DEFINE_MUTEX(block_subsys_lock);

/*
 * Can be deleted altogether. Later.
 *
 */
static struct blk_major_name {
        struct blk_major_name *next;
        int major;
        char name[16];
} *major_names[BLKDEV_MAJOR_HASH_SIZE];

/* index in the above - for now: assume no multimajor ranges */
static inline int major_to_index(int major)
{
        return major % BLKDEV_MAJOR_HASH_SIZE;
}

#ifdef CONFIG_PROC_FS

void blkdev_show(struct seq_file *f, off_t offset)
{
        struct blk_major_name *dp;

        if (offset < BLKDEV_MAJOR_HASH_SIZE) {
                mutex_lock(&block_subsys_lock);
                for (dp = major_names[offset]; dp; dp = dp->next)
                        seq_printf(f, "%3d %s\n", dp->major, dp->name);
                mutex_unlock(&block_subsys_lock);
        }
}

#endif /* CONFIG_PROC_FS */

int register_blkdev(unsigned int major, const char *name)
{
        struct blk_major_name **n, *p;
        int index, ret = 0;

        mutex_lock(&block_subsys_lock);

        /* temporary */
        if (major == 0) {
                for (index = ARRAY_SIZE(major_names)-1; index > 0; index--) {
                        if (major_names[index] == NULL)
                                break;
                }

                if (index == 0) {
                        printk("register_blkdev: failed to get major for %s\n",
                               name);
                        ret = -EBUSY;
                        goto out;
                }
                major = index;
                ret = major;
        }

        p = kmalloc(sizeof(struct blk_major_name), GFP_KERNEL);
        if (p == NULL) {
                ret = -ENOMEM;
                goto out;
        }

        p->major = major;
        strlcpy(p->name, name, sizeof(p->name));
        p->next = NULL;
        index = major_to_index(major);

        for (n = &major_names[index]; *n; n = &(*n)->next) {
                if ((*n)->major == major)
                        break;
        }
        if (!*n)
                *n = p;
        else
                ret = -EBUSY;

        if (ret < 0) {
                printk("register_blkdev: cannot get major %d for %s\n",
                       major, name);
                kfree(p);
        }
out:
        mutex_unlock(&block_subsys_lock);
        return ret;
}

EXPORT_SYMBOL(register_blkdev);

/* todo: make void - error printk here */
int unregister_blkdev(unsigned int major, const char *name)
{
        struct blk_major_name **n;
        struct blk_major_name *p = NULL;
        int index = major_to_index(major);
        int ret = 0;

        mutex_lock(&block_subsys_lock);
        for (n = &major_names[index]; *n; n = &(*n)->next)
                if ((*n)->major == major)
                        break;
        if (!*n || strcmp((*n)->name, name))
                ret = -EINVAL;
        else {
                p = *n;
                *n = p->next;
        }
        mutex_unlock(&block_subsys_lock);
        kfree(p);

        return ret;
}

EXPORT_SYMBOL(unregister_blkdev);

static struct kobj_map *bdev_map;

/*
 * Register device numbers dev..(dev+range-1)
 * range must be nonzero
 * The hash chain is sorted on range, so that subranges can override.
 */
void blk_register_region(dev_t dev, unsigned long range, struct module *module,
                         struct kobject *(*probe)(dev_t, int *, void *),
                         int (*lock)(dev_t, void *), void *data)
{
        kobj_map(bdev_map, dev, range, module, probe, lock, data);
}

EXPORT_SYMBOL(blk_register_region);

void blk_unregister_region(dev_t dev, unsigned long range)
{
        kobj_unmap(bdev_map, dev, range);
}

EXPORT_SYMBOL(blk_unregister_region);

static struct kobject *exact_match(dev_t dev, int *part, void *data)
{
        struct gendisk *p = data;
        return &p->kobj;
}

static int exact_lock(dev_t dev, void *data)
{
        struct gendisk *p = data;

        if (!get_disk(p))
                return -1;
        return 0;
}

/**
 * add_disk - add partitioning information to kernel list
 * @disk: per-device partitioning information
 *
 * This function registers the partitioning information in @disk
 * with the kernel.
 */
void add_disk(struct gendisk *disk)
{
        disk->flags |= GENHD_FL_UP;
        blk_register_region(MKDEV(disk->major, disk->first_minor),
                            disk->minors, NULL, exact_match, exact_lock, disk);
        register_disk(disk);
        blk_register_queue(disk);
}

EXPORT_SYMBOL(add_disk);
EXPORT_SYMBOL(del_gendisk);     /* in partitions/check.c */

void unlink_gendisk(struct gendisk *disk)
{
        blk_unregister_queue(disk);
        blk_unregister_region(MKDEV(disk->major, disk->first_minor),
                              disk->minors);
}

#define to_disk(obj) container_of(obj,struct gendisk,kobj)

/**
 * get_gendisk - get partitioning information for a given device
 * @dev: device to get partitioning information for
 *
 * This function gets the structure containing partitioning
 * information for the given device @dev.
 */
struct gendisk *get_gendisk(dev_t dev, int *part)
{
        struct kobject *kobj = kobj_lookup(bdev_map, dev, part);
        return  kobj ? to_disk(kobj) : NULL;
}

#ifdef CONFIG_PROC_FS
/* iterator */
static void *part_start(struct seq_file *part, loff_t *pos)
{
        struct list_head *p;
        loff_t l = *pos;

        mutex_lock(&block_subsys_lock);
        list_for_each(p, &block_subsys.kset.list)
                if (!l--)
                        return list_entry(p, struct gendisk, kobj.entry);
        return NULL;
}

static void *part_next(struct seq_file *part, void *v, loff_t *pos)
{
        struct list_head *p = ((struct gendisk *)v)->kobj.entry.next;
        ++*pos;
        return p==&block_subsys.kset.list ? NULL : 
                list_entry(p, struct gendisk, kobj.entry);
}

static void part_stop(struct seq_file *part, void *v)
{
        mutex_unlock(&block_subsys_lock);
}

static int show_partition(struct seq_file *part, void *v)
{
        struct gendisk *sgp = v;
        int n;
        char buf[BDEVNAME_SIZE];

        if (&sgp->kobj.entry == block_subsys.kset.list.next)
                seq_puts(part, "major minor  #blocks  name\n\n");

        /* Don't show non-partitionable removeable devices or empty devices */
        if (!get_capacity(sgp) ||
                        (sgp->minors == 1 && (sgp->flags & GENHD_FL_REMOVABLE)))
                return 0;
        if (sgp->flags & GENHD_FL_SUPPRESS_PARTITION_INFO)
                return 0;

        /* show the full disk and all non-0 size partitions of it */
        seq_printf(part, "%4d  %4d %10llu %s\n",
                sgp->major, sgp->first_minor,
                (unsigned long long)get_capacity(sgp) >> 1,
                disk_name(sgp, 0, buf));
        for (n = 0; n < sgp->minors - 1; n++) {
                if (!sgp->part[n])
                        continue;
                if (sgp->part[n]->nr_sects == 0)
                        continue;
                seq_printf(part, "%4d  %4d %10llu %s\n",
                        sgp->major, n + 1 + sgp->first_minor,
                        (unsigned long long)sgp->part[n]->nr_sects >> 1 ,
                        disk_name(sgp, n + 1, buf));
        }

        return 0;
}

struct seq_operations partitions_op = {
        .start =part_start,
        .next = part_next,
        .stop = part_stop,
        .show = show_partition
};
#endif


extern int blk_dev_init(void);

static struct kobject *base_probe(dev_t dev, int *part, void *data)
{
        if (request_module("block-major-%d-%d", MAJOR(dev), MINOR(dev)) > 0)
                /* Make old-style 2.4 aliases work */
                request_module("block-major-%d", MAJOR(dev));
        return NULL;
}

static int __init genhd_device_init(void)
{
        bdev_map = kobj_map_init(base_probe, &block_subsys_lock);
        blk_dev_init();
        subsystem_register(&block_subsys);
        return 0;
}

subsys_initcall(genhd_device_init);



/*
 * kobject & sysfs bindings for block devices
 */
static ssize_t disk_attr_show(struct kobject *kobj, struct attribute *attr,
                              char *page)
{
        struct gendisk *disk = to_disk(kobj);
        struct disk_attribute *disk_attr =
                container_of(attr,struct disk_attribute,attr);
        ssize_t ret = -EIO;

        if (disk_attr->show)
                ret = disk_attr->show(disk,page);
        return ret;
}

static ssize_t disk_attr_store(struct kobject * kobj, struct attribute * attr,
                               const char *page, size_t count)
{
        struct gendisk *disk = to_disk(kobj);
        struct disk_attribute *disk_attr =
                container_of(attr,struct disk_attribute,attr);
        ssize_t ret = 0;

        if (disk_attr->store)
                ret = disk_attr->store(disk, page, count);
        return ret;
}

static struct sysfs_ops disk_sysfs_ops = {
        .show   = &disk_attr_show,
        .store  = &disk_attr_store,
};

static ssize_t disk_uevent_store(struct gendisk * disk,
                                 const char *buf, size_t count)
{
        kobject_uevent(&disk->kobj, KOBJ_ADD);
        return count;
}
static ssize_t disk_dev_read(struct gendisk * disk, char *page)
{
        dev_t base = MKDEV(disk->major, disk->first_minor); 
        return print_dev_t(page, base);
}
static ssize_t disk_range_read(struct gendisk * disk, char *page)
{
        return sprintf(page, "%d\n", disk->minors);
}
static ssize_t disk_removable_read(struct gendisk * disk, char *page)
{
        return sprintf(page, "%d\n",
                       (disk->flags & GENHD_FL_REMOVABLE ? 1 : 0));

}
static ssize_t disk_size_read(struct gendisk * disk, char *page)
{
        return sprintf(page, "%llu\n", (unsigned long long)get_capacity(disk));
}

static ssize_t disk_stats_read(struct gendisk * disk, char *page)
{
        preempt_disable();
        disk_round_stats(disk);
        preempt_enable();
        return sprintf(page,
                "%8lu %8lu %8llu %8u "
                "%8lu %8lu %8llu %8u "
                "%8u %8u %8u"
                "\n",
                disk_stat_read(disk, ios[READ]),
                disk_stat_read(disk, merges[READ]),
                (unsigned long long)disk_stat_read(disk, sectors[READ]),
                jiffies_to_msecs(disk_stat_read(disk, ticks[READ])),
                disk_stat_read(disk, ios[WRITE]),
                disk_stat_read(disk, merges[WRITE]),
                (unsigned long long)disk_stat_read(disk, sectors[WRITE]),
                jiffies_to_msecs(disk_stat_read(disk, ticks[WRITE])),
                disk->in_flight,
                jiffies_to_msecs(disk_stat_read(disk, io_ticks)),
                jiffies_to_msecs(disk_stat_read(disk, time_in_queue)));
}
static struct disk_attribute disk_attr_uevent = {
        .attr = {.name = "uevent", .mode = S_IWUSR },
        .store  = disk_uevent_store
};
static struct disk_attribute disk_attr_dev = {
        .attr = {.name = "dev", .mode = S_IRUGO },
        .show   = disk_dev_read
};
static struct disk_attribute disk_attr_range = {
        .attr = {.name = "range", .mode = S_IRUGO },
        .show   = disk_range_read
};
static struct disk_attribute disk_attr_removable = {
        .attr = {.name = "removable", .mode = S_IRUGO },
        .show   = disk_removable_read
};
static struct disk_attribute disk_attr_size = {
        .attr = {.name = "size", .mode = S_IRUGO },
        .show   = disk_size_read
};
static struct disk_attribute disk_attr_stat = {
        .attr = {.name = "stat", .mode = S_IRUGO },
        .show   = disk_stats_read
};

static struct attribute * default_attrs[] = {
        &disk_attr_uevent.attr,
        &disk_attr_dev.attr,
        &disk_attr_range.attr,
        &disk_attr_removable.attr,
        &disk_attr_size.attr,
        &disk_attr_stat.attr,
        NULL,
};

static void disk_release(struct kobject * kobj)
{
        struct gendisk *disk = to_disk(kobj);
        kfree(disk->random);
        kfree(disk->part);
        free_disk_stats(disk);
        kfree(disk);
}

static struct kobj_type ktype_block = {
        .release        = disk_release,
        .sysfs_ops      = &disk_sysfs_ops,
        .default_attrs  = default_attrs,
};

extern struct kobj_type ktype_part;

static int block_uevent_filter(struct kset *kset, struct kobject *kobj)
{
        struct kobj_type *ktype = get_ktype(kobj);

        return ((ktype == &ktype_block) || (ktype == &ktype_part));
}

static int block_uevent(struct kset *kset, struct kobject *kobj, char **envp,
                         int num_envp, char *buffer, int buffer_size)
{
        struct kobj_type *ktype = get_ktype(kobj);
        struct device *physdev;
        struct gendisk *disk;
        struct hd_struct *part;
        int length = 0;
        int i = 0;

        if (ktype == &ktype_block) {
                disk = container_of(kobj, struct gendisk, kobj);
                add_uevent_var(envp, num_envp, &i, buffer, buffer_size,
                               &length, "MINOR=%u", disk->first_minor);
        } else if (ktype == &ktype_part) {
                disk = container_of(kobj->parent, struct gendisk, kobj);
                part = container_of(kobj, struct hd_struct, kobj);
                add_uevent_var(envp, num_envp, &i, buffer, buffer_size,
                               &length, "MINOR=%u",
                               disk->first_minor + part->partno);
        } else
                return 0;

        add_uevent_var(envp, num_envp, &i, buffer, buffer_size, &length,
                       "MAJOR=%u", disk->major);

        /* add physical device, backing this device  */
        physdev = disk->driverfs_dev;
        if (physdev) {
                char *path = kobject_get_path(&physdev->kobj, GFP_KERNEL);

                add_uevent_var(envp, num_envp, &i, buffer, buffer_size,
                               &length, "PHYSDEVPATH=%s", path);
                kfree(path);

                if (physdev->bus)
                        add_uevent_var(envp, num_envp, &i,
                                       buffer, buffer_size, &length,
                                       "PHYSDEVBUS=%s",
                                       physdev->bus->name);

                if (physdev->driver)
                        add_uevent_var(envp, num_envp, &i,
                                       buffer, buffer_size, &length,
                                       "PHYSDEVDRIVER=%s",
                                       physdev->driver->name);
        }

        /* terminate, set to next free slot, shrink available space */
        envp[i] = NULL;
        envp = &envp[i];
        num_envp -= i;
        buffer = &buffer[length];
        buffer_size -= length;

        return 0;
}

static struct kset_uevent_ops block_uevent_ops = {
        .filter         = block_uevent_filter,
        .uevent         = block_uevent,
};

decl_subsys(block, &ktype_block, &block_uevent_ops);

/*
 * aggregate disk stat collector.  Uses the same stats that the sysfs
 * entries do, above, but makes them available through one seq_file.
 * Watching a few disks may be efficient through sysfs, but watching
 * all of them will be more efficient through this interface.
 *
 * The output looks suspiciously like /proc/partitions with a bunch of
 * extra fields.
 */

/* iterator */
static void *diskstats_start(struct seq_file *part, loff_t *pos)
{
        loff_t k = *pos;
        struct list_head *p;

        mutex_lock(&block_subsys_lock);
        list_for_each(p, &block_subsys.kset.list)
                if (!k--)
                        return list_entry(p, struct gendisk, kobj.entry);
        return NULL;
}

static void *diskstats_next(struct seq_file *part, void *v, loff_t *pos)
{
        struct list_head *p = ((struct gendisk *)v)->kobj.entry.next;
        ++*pos;
        return p==&block_subsys.kset.list ? NULL :
                list_entry(p, struct gendisk, kobj.entry);
}

static void diskstats_stop(struct seq_file *part, void *v)
{
        mutex_unlock(&block_subsys_lock);
}

static int diskstats_show(struct seq_file *s, void *v)
{
        struct gendisk *gp = v;
        char buf[BDEVNAME_SIZE];
        int n = 0;

        /*
        if (&sgp->kobj.entry == block_subsys.kset.list.next)
                seq_puts(s,     "major minor name"
                                "     rio rmerge rsect ruse wio wmerge "
                                "wsect wuse running use aveq"
                                "\n\n");
        */
 
        preempt_disable();
        disk_round_stats(gp);
        preempt_enable();
        seq_printf(s, "%4d %4d %s %lu %lu %llu %u %lu %lu %llu %u %u %u %u\n",
                gp->major, n + gp->first_minor, disk_name(gp, n, buf),
                disk_stat_read(gp, ios[0]), disk_stat_read(gp, merges[0]),
                (unsigned long long)disk_stat_read(gp, sectors[0]),
                jiffies_to_msecs(disk_stat_read(gp, ticks[0])),
                disk_stat_read(gp, ios[1]), disk_stat_read(gp, merges[1]),
                (unsigned long long)disk_stat_read(gp, sectors[1]),
                jiffies_to_msecs(disk_stat_read(gp, ticks[1])),
                gp->in_flight,
                jiffies_to_msecs(disk_stat_read(gp, io_ticks)),
                jiffies_to_msecs(disk_stat_read(gp, time_in_queue)));

        /* now show all non-0 size partitions of it */
        for (n = 0; n < gp->minors - 1; n++) {
                struct hd_struct *hd = gp->part[n];

                if (hd && hd->nr_sects)
                        seq_printf(s, "%4d %4d %s %u %u %u %u\n",
                                gp->major, n + gp->first_minor + 1,
                                disk_name(gp, n + 1, buf),
                                hd->ios[0], hd->sectors[0],
                                hd->ios[1], hd->sectors[1]);
        }
 
        return 0;
}

struct seq_operations diskstats_op = {
        .start  = diskstats_start,
        .next   = diskstats_next,
        .stop   = diskstats_stop,
        .show   = diskstats_show
};

struct gendisk *alloc_disk(int minors)
{
        return alloc_disk_node(minors, -1);
}

struct gendisk *alloc_disk_node(int minors, int node_id)
{
        struct gendisk *disk;

        disk = kmalloc_node(sizeof(struct gendisk), GFP_KERNEL, node_id);
        if (disk) {
                memset(disk, 0, sizeof(struct gendisk));
                if (!init_disk_stats(disk)) {
                        kfree(disk);
                        return NULL;
                }
                if (minors > 1) {
                        int size = (minors - 1) * sizeof(struct hd_struct *);
                        disk->part = kmalloc_node(size, GFP_KERNEL, node_id);
                        if (!disk->part) {
                                kfree(disk);
                                return NULL;
                        }
                        memset(disk->part, 0, size);
                }
                disk->minors = minors;
                kobj_set_kset_s(disk,block_subsys);
                kobject_init(&disk->kobj);
                rand_initialize_disk(disk);
        }
        return disk;
}

EXPORT_SYMBOL(alloc_disk);
EXPORT_SYMBOL(alloc_disk_node);

struct kobject *get_disk(struct gendisk *disk)
{
        struct module *owner;
        struct kobject *kobj;

        if (!disk->fops)
                return NULL;
        owner = disk->fops->owner;
        if (owner && !try_module_get(owner))
                return NULL;
        kobj = kobject_get(&disk->kobj);
        if (kobj == NULL) {
                module_put(owner);
                return NULL;
        }
        return kobj;

}

EXPORT_SYMBOL(get_disk);

void put_disk(struct gendisk *disk)
{
        if (disk)
                kobject_put(&disk->kobj);
}

EXPORT_SYMBOL(put_disk);

void set_device_ro(struct block_device *bdev, int flag)
{
        if (bdev->bd_contains != bdev)
                bdev->bd_part->policy = flag;
        else
                bdev->bd_disk->policy = flag;
}

EXPORT_SYMBOL(set_device_ro);

void set_disk_ro(struct gendisk *disk, int flag)
{
        int i;
        disk->policy = flag;
        for (i = 0; i < disk->minors - 1; i++)
                if (disk->part[i]) disk->part[i]->policy = flag;
}

EXPORT_SYMBOL(set_disk_ro);

int bdev_read_only(struct block_device *bdev)
{
        if (!bdev)
                return 0;
        else if (bdev->bd_contains != bdev)
                return bdev->bd_part->policy;
        else
                return bdev->bd_disk->policy;
}

EXPORT_SYMBOL(bdev_read_only);

int invalidate_partition(struct gendisk *disk, int index)
{
        int res = 0;
        struct block_device *bdev = bdget_disk(disk, index);
        if (bdev) {
                fsync_bdev(bdev);
                res = __invalidate_device(bdev);
                bdput(bdev);
        }
        return res;
}

EXPORT_SYMBOL(invalidate_partition);